Compact shockproof electrical discharge apparatus and means for producing the same



Jan. 1, 1935. w, A. M KAY 1,986,482

COMPACT SHOCKPROOF ELECTRICAL DISCHARGE APPARATUS AND MEANS FOR PRODUCING THE SAME Filed Nov. 3, 1951 2 Sheets-Sheet l I'I'H I IH If! Wm! INVENTOR J5 hf. 4. M6 KAY ATTORNE Patented Jan. 1, 1935 UNITED STATES PATENT OFFICE COMPACT SHOCKPROOF CHARGE APPARATUS AND THE SAME raonucme Application November 3, 1931, Serial No.

11 Claims.

This invention relates to electrical discharge devices and means associated therewith adapted are operated at voltages ranging from about 40,000 volts upward. These voltages, impressed across the high tension electrode terminals of the tubes, are generally derived from sion transformers and the like.

sealed therein, electrodes outside of the envelope. At least two of these electrode terminals are connected to a high tenmedia having different dielectric' ELECTRICAL DISe' MEANS FOR 572,785 (cl. 25H!) It is well known that the ambient medium at the shortest path that no external electrical discharge, such as an are or spark discharg will take place between these terminals when the tube is operated at its working voltage in that medium, the tube being otherwise designed, as for example, to prevent electrical leakage between the te over the exterior surface of the glass envelope. This certain minimum length of the ambient medium gap depends on the particular ambient medium and characteristics thereof, and the working voltage of the tube, and will hereinafter be rebeen proposed to employ oil as the ambient medium, so that the distance between the high tension electrode terminals may be materially reduced.

From the time tube, however, it has been common practice to The X-ray tube electrodes are electrically connected to the appropriate windings of the trans any arcing the tubeare separated by a distance less than md the workman must oil coated tubes and wires;

the air gap equivalent of the working voltage of the tube.

Because the X-ray tube is immersed in oil, a

construction of this character has a number of disadvantages, some .of which are as follows: any X-ray tube replacement is an unpleasant and time consuming task because the head of the casing must be removed before the workman may disconnect the electrical. tube connections, necessarily handle the if the X-ray tube should break and the parts of .the tube settle on the transformer units it is necessary to drain the oil in order that these parts may be removed; tube replacements generally cannot be ,made by an ordinary operator but require a skilled operator who comprehends which of the terminals are to be electrically connected to the appropriate leads of the transformer; some of the useful X-rays are absorbed by the oil thus diminishing the effective X-ray output of the apparatus and loss in definition is effected because of the generation of secondary X-rays.

My invention in one of its specific aspects is directed to an X-ray apparatus of thesimple, compact and shock proof type which has all of the advantages of the constructions heretofore proposed, without any of the disadvantages heretofore mentioned, and concerns itself not only with X-ray apparatus form of X-ray tube as well.

Briefly stated my invention includes a simple and compact X-ray, or other electrical apparatus, of comparatively light weight, which comprises a casing filled with oil and has either one or more transformers contained therein, and a novel compact unit supported by said casing, having its outer surface surrounded by said oil and comprising an X-ray tube, or electrical discharge device, in an ambient medium of air, or the like, and a novel dielectric housing member having means for supporting the tube or device and for cooperating there 'th to increase the ambient gap of said tube or device.

The X-ray or electrical discharge tube, also of novel design and contained within said housing member, is supported thereby and has one of its high tension electrode terminals electrically connected to the socket connected to one side of a high tension power source, and its other high tension electrode terminal connected to the other side of the high tension power source by any suitable means. 'I hese terminals are spaced from each other a distance measured outside the tube w ch is materially less than the critical ambient medium gap of the tube, consideration also being given to the matter of electrical leakage, as explained heretofore.

As will be hereinafter more fully described the housing member with its baflle means is so associated with this tube that the tube is capable of operating at its working voltage without external arcing between its high tension electrode terminals, because the ambient medium gap of the tube is so lengthened that it is at least as great as, and preferably greater than its critical ambient medium gap.

but with. a novel An object of my invention is to provide an electrical discharge apparatus which is simple, compact and vof light weight and afiords adequate protection from the risk of electrical shocks, burns, stray X-radiation and electrical arcing between the high tension electrode terminals and permits ready insertion or replacements of the discharge tube by unskilled persons.

A further object of my invention is to provide an X-ray apparatus of the shock-proof type which embodies an X-ray tube of, compact form having a relatively long electrical leakage path between its high tension terminals and capable of operating in an ambient gaseous medium without any arcing outside the tube between its high tension electrode terminals, at the operating voltage of the tube, even though the spaced relation of the terminals of the tube is less than that normally required for such a voltage in that medium.

Another object of my invention is to provide an X-ray apparatus, embodying an X-ray tube adapted to operate in an ambient gaseous medium at its working voltage without any danger of arcing outside of the tube and between its high tension electrode terminals, even when the distance between these terminals, measured outside the tube, is materially less than the minimum length of the ambient gaseous gap for such a voltage in the gaseous medium so that no arcing will occur outside the tube and between these terminals.

Another object of my invention is to provide an X-ray apparatus embodying an X-ray tube in an ambient medium and having a spark over gap between its high tension terminals of a length insufiicient to prevent spark over therebetween at the maximum working voltage of the tube, and a means cooperating therewith so that the length of the spark over gap is so increased that no spark over will occur between these terminals in that medium at such voltage.

Another object of my invention isto provide a simple, compact and shock-proof X-ray apparatus adapted to permit X-ray tube replacements in a facile and expeditious manner even by an unskilled operator.

Another object of my invention is to provide a means adapted to be combined with my novel X-ray tube to lengthen the ambient medium gap of the tube per se.

A still further object of my invention is to provide a dielectric means adapted to be combined with an X-ray tube so that the tube is capable of operating in an ambient gaseous medium at its working voltage without outside arcing even though the high tension electrode terminals of the tube measured outside the tube are separated a distance less than its critical ambient gaseous gap.

A still further object of my invention is to proelevation and others diagrammatically, of an x-ray apparatus embodying my invention;

2 represents a sectional view along line IIII of Figure-1:

Figure 3 is a fragmentary cross sectional view with some of the parts in elevation of a modification of a portionof the apparatus shown in Figure 1- Figure 4 is a fragmentary cross sectional view with some of. the parts in elevation of another modification of a portion of the apparatus shown in Figure 1; and

Figure 5 is a fragmentary cross sectional view with some of the parts in elevation of another modification of a portion of the apparatus shown in Figure 1.

As shown in Figure 1, one embodiment of my invention includes oil immersed transformer units, an X-ray tube in air, and dielectric baflle members associated therewith -to provide an efilcient, electrical shock proof, simple, compact and light weight X-ray apparatus which may be expeditiously assembled and repaired.

According to my invention, the X-ray tube envelope 9, having a cylindrical body portion 10, a generally hemispherical upper end 11 and a lower end in the form of a plurality of suitably spaced cylindrical folds, sleeves or plaits 12, 13 and 14 extending longitudinally of and within the body 10 to provide a relatively long electrical leakage path between the high tension electrode terminals hereinafter referred to.

The innermost plait or fold 14 is shorter than the plaits or folds 12 is in the form of substantially and 13 and an open reentrant tube with a free upper end. Sealed to the free end of this reentrant tube is a tubular metallic sleeve member 15 which supports both an anode 16 and an anode stem 17. This anode stem 17, extending outside of the envelope, surrounded by the reentrant tube, being in line with the anode 16, has a threaded free end.

A second reentrant tube 18, also composed of insulating material, such pyrex glass is fused to the inner wall of the fold or plait 13 at a position above the anode sleeve supporting member 15. This reentrant tube 18 surrounds a portion of the anode 16 and like the plait or fold 14 extends longitudinally of and within the tube with its free end uppermost. Between the anode 16 and the inner periphery of the reentrant tube 18 is a spring sleeve 19 firmly secured to the anode and adapted to frictionally engage the inner periphery of the reentrant tube 18 to serve as a shock absorbing and distributing means therefor and also to assist in supporting the-anode.

The anode 16 which is preferably composed of copper has a free end 20 which is provided with a target of tungsten or the like and which is capable of emitting X-rays when subjected to electronic bombardment by electrons emitted from a suitable cathode, such as a helical filament 21 of tantalum, tungsten, or any other suitable material.

At the upper portion of the envelope 9 there 'may be provided a chrome-iron or other suitable X-ray screen of appropriate thickness dispmd around the upper end of the anode and serving to screen out undesirable X-rays. This X-ray screen is of reduced length and comprises a cylinder 23 with its bottom edge in the ap proximate plane of the upper end of the anode 16, and a cap 24, having a suitable opening 25 as quartz, silica or of which is in frictional contact with the inner periphery of the envelope 9 to hold the screen in position.

proximity to the hemispherical portion 11. One of the lead-in wires 30 is electrically insulated from the screen by means of an insulating bead 32 secured to the cap 24.

Each of the terminals 31 is spaced from the anode extension 17 a distance measured outside the tube which is less thanthe critical ambient medium gap of the tube.

In accordance my invention, the ambient medium gap of the tube may be so lengthened that the tube may be safely operated at its its working voltages without any spark over between these terminals at For this P pose, one of electric means which I may employ in combination with the X-ray tube hereinbefore described is a substantially cup-shaped member 33 composed of a suitable dielectric material, such as glass, ebonite, hard rubber, porcelain, a phenolic condensation product or the like, and preferably phenolic condensation product because the latter may be readily molded.

The cup shaped member may comprise a single homogeneous phenolic condensation product or glass structure having embedded in its base an members 38 and 39 extending upwardly from the base 3'7, with the center point of the .base

being in approximate coincidence with the center line of the respective baflles.

The length of the baflles 38 and 39 may be less than the length of the envelope plaits or folds 14 and 13 respectively, and the spacing of these bailles may be such that they readily fit and extend upwardly between the anode extension 17 and the plait or fold 14 and between the plaits 12 and 13 respectively upon assemblage of my novel X-ray tube and the dielectric housing 33.

The cup-shaped member 33 may be readily shaped by moulding phenolic condensation product or glass, and the socket 34 may be readily united therewith during the moulding operation to form a fluid tight seal therebe'tween although any other means of forming a fluid tight seal between the socket 34 and the dielectric cup shaped member 33 may be employed. The socket 34 which is dependably secured to the base of the cup has its upper end free of the dielectric and has a threaded recess inwardly along the axis thereof.

That portion of the socket 34 which is outside of and depends from the base 3'1 has thereon a radiator comprised of a plurality of heat conducting fins 40. This socket 34 has two important and useful purposes, namely, that of an electrical connecting means for the threaded end of the anode stem 1'1, and that of a heat conducting means which aids in conveying the heat energy from the anode 16. Furthermore it assures accurate positioning of the X-ray tube so that the target is in proper alignment for the taking of X-ray pictures.

The X-ray tube is assembled with the cupshaped dielectric member by merely screwing the threaded end of the anode extension 17 into the threaded socket 34, to provide a structure as shown in Figure 1 with the cylindrical baffle means 38 and 39 extending upwardly from the dielectric cup 33 and spaced respectively between the anode stem 17 and the plait or fold 14' andbetween the plaits or folds 12 and 13.

The distance between the anode extension 17 and the plait or fold 14, between the plaits or folds 12 and 13, and the distance of the respective cylindrical dielectric baflle members 38 and 39 from the center of the base plate 37 are preferably such that when the X-ray tube is screwed into the socket of the electrical conductor 34, the walls of the dielectric bailles 38 and 39 will be free from any hard contact with the folds or plaits of the envelope or the anode extension.

In practicing my invention there may be provided a novel relatively short X-ray tube in an ambient gaseous medium, such as air, and having its high tension electrode terminals 17 and 31 spaced from each other, measuredoutside the tube, a distance indicated by the dot-dash line and being materially less than its critical ambient gaseous gap, and having an envelope characterized by a plurality of spaced plaits or folds 12, 13 and 14 at its lower end.

In further accordance with my invention there may be provided a novel, simple, compact shock proof u 't of light weight comprising this X-ray tube in an ambient gaseous medium of air or the like together with a dielectric cup 33 surrounding the sides and bottom of the tube envelope and with dielectric baflles 38 and 39 extending upwardly from the bottom of the cup 33 and respectively into the spaces between the folds or plaits 12 and 13 and the anode extension 17 and the plait or fold 14 to lengthen the ambient medium gap of thetube so that it is at least as great as and preferably greater than its critical ambient medium gap. This x-ray tube embodied in a unit of this construction may be operated-,at its working voltage without any danger of arcing outside the tube and between its high tension electrode terminals because the length of the shortest path in the continuous ambient gaseous medium between these terminals or the length of what I term the ambient gaseous gap," indicated by the dotted line, is at least as great as, and preferably greater than, the necessary minimum length of the ambient gaseous gap so that no arcing will take place upon operating the tube in a gaseous medium at its working voltage. This minimum length, as heretofore explained, I term the critical ambient gaseous gap.

Consequently it is apparent that by employing a unit of this or any generally similar construction the length of the ambient gaseous gap between the high tension electrode terminals of an X-ray tube may be materially greater than the critical ambient gaseous gap even where the distance between these terminals measured outside of the tube envelope is materially less than its critical ambient gaseous gap. By virtue of a construction of this character the length of X-ray tube envelope and anode may be materially reduced to decrease the length of the heat conducting path, minimize the danger of breakage and' reduce manufacturing costs, and to provide a compact relatively short tube, having a relatively long electrical leakage path, and adapted to operate without any danger of arcing outside of the envelope between the high tension terminals.

The dimensions of the bottom, sides and baflles of the dielectric cup is a mere matter of economical, mechanical and electrical design depending on the nature of the dielectric, the length of the X-ray tube, the length of the plaits or folds of the envelope, the distance between the high tension terminals, the nature of the ambient medium, and upon the magnitude of the voltage to be impressed between the high tension electrode terminals of the tube.

The unit, comprising the dielectric cup 33 and the X-ray tube associated therewith by means of the anode extension 17 secured to the socket 34, may be connected to any appropriate electrical supply, and may be supported by any suitable means.

It may be preferably combined with an oil filled transformer casing 41 in order to provide a compact means adapted to be readily mounted on a supporting structure and so that the oil in the casing may exert a cooling action on the anode by virtue of the fins 40 and a portion of the socket 34 being immersed therein.

The transformer casing 41 is of any appropriate size and has a top 42 with a circular opening of suitable diameter which permits the insertion therein of the tube housing dielectric cup 33. The flange 36 of the cup rests on the top plate 42 of the casing and is firmly secured thereto to form an oil tight seal therewith to prevent any leaking therethrough of the oil which surrounds the outer surface of the cup and a plurality of transformers 43 and 44 totally immersed therein.

The transformers 43 and 44 are respectively high tension and low tension transformers, with primary windings 45 and 46, each connected across a suitable power supply secondary windings 48 and One terminal, of the secondary winding 48 of the high tension transformer is connected to the free end of the socket 34 by means of a connecting wire 50 and the other end of this secondary winding 48 is connected to one of ,the cathode terminals 31 by means of a wire 51 and a spring clip connector (not shown).

The cathode filament 21 is heated by means of current from the low voltage transformer 44 having one terminal of its secondary winding 49 electrically connected to the cathode terminal 31 by means of a wire 52 and a spring clip (not shown) and the other terminal of this winding 49 is connected to the first mentioned cathode terminal 31 by means of a wire 53 connected thereto and to the high tension wire 51.

To provide additional safeguards against any danger of electrical shocks, I preferably electrically connect by means of a wire 54 the easing with one of the terminals of the secondary winding 48 of the high tension transformer, and ground the casing in any suitable manner by means of the ground connection 55.

In order that the X-ray bulb may be completely surrounded with a protective medium, I provide a cap 56 of bakelite or any other suitable material over the hemispherical portion- 11 of the envelope of the X-ray tube and secured to the top of the transformer casing in any suitable manner.

Although the screen, ofl and transformer casing absorb substantially all of the undesirable X-radiation, a lead band 57, preferably but not necessarily secured to the inner side of the bakelite structure 35, may be provided to overlie the juncture between the cap 56 and the cup 33 and may be of such a. width as to extend upwardly an appreciable distance along the inner surface of the cap and downwardly an appreciable distance along the wall of the bakelite cup 33 to absorb any undesirable stray X-radiation which might not be absorbed by the screen, oil or transformer casing. This 47, and having 49 respectively.

. band may be electrically connected to the oathode terminal by any suitable means.

The cost of manufacturing X-ray apparatus, and particularly the X-ray tube per se, may be materially reduced by employing a transformer casing and a dielectric cup of suflicient depth so that the upper level of the oil within the casing is in close proximity to and preferably materially above the upper limit of the envelope of the tube. In a construction of this character,

the cylindrical portion 23 of the metallic screen,

may be completely eliminated because the oil and the transformer casing will absorb any undesirable x-radiations. Therefore, in place of the screen heretofore described I may employ a screen consisting of a circular plate, similar to plate 24 of appropriate thickness and having an opening therein and a spring sleeve, similar to sleeve 26, secured to the outer periphery of the plate by means of suitable pins.

It is also within the scope of my invention to have the unit embodying X-ray tube and the dielectric cup mounted on any suitable supportng means other than and remote from the transformer casing.

Although I have described one embodiment of my invention with particularity, I am not limited to this embodiment because the invention is susceptible to a number of modifications. It is within the purview of this invention to include and into the space V the proximity of said as shown in igure 5, similar in all respects to the construction shown in Figin'e 1, except that the X-ray tubemay have but one reentrant fold or plait of convenient length suitably spaced from the anode extension, and the bottom of the dielectric housing may have but one dielectric cylindrical Me of appropriate dimensions extending upwardly between the anode extension and the reentrant fold or tube.

Another modification of my invention is shown in Figure 3 and is similar in all respects to the construction shown in Figure 1 except that the bottom of the dielectric cup has but one cylinder baifle 39 which baiiie is located between the folds 12 and 13 of the x-ray tube.

A further modification of my invention comprises a structure similar in all respects to the structure shown in Figure 1 except for certain modifications illustrated in Figure 4 and hereinafter described.

In the construction shown in Figure 1, the dielectric bame means 38, located between the anode stem 17 and the plait or fold 14, is integral with the bottom of the dielectric housing member 33. Instead of having the baflie means located between the anode stem and its adjacent plait or fold, integral with the bottom of the dielectric housing member, I may provide a cylindrical baiiie means 60, with its inner wall spaced from the anode stem and rigidly secured thereto by an inwardly extending flange 61 at the upper end of the cylindrical baille means 60 and an integral part thereof.

The lower or free end of the battle means 60 is appropriately threaded, and the bottom of the dielectric cup or housing member has 'an appropriately threaded recess 62 adapted to form a tight Joint with the threaded end of the battle means. In a construction of this character there is provided an X-ray tube similar to the one heretofore described and differing therefrom in having a dielectric baflie member rigidly secured to its anode stem.

This X-ray tube may readily be secured to the modified dielectric housing by simultaneously screwing the threaded free end of both the bailie member and the anode extension into the threaded recess of the dielectric housing member and the electric socket respectively.

Bythe term working voltages" of the tube as hereinbefore referred to and as employed in the appended claims, I mean the normal operating voltages of the tube and also the surge voltages caused by the energization and deenergization of the tube on the make and "break of its circuit, the latter of which are considerably greater than the former.

Although I have described the invention with specific reference to X-ray tubes it is obvious to those skilled in the art it may be applied to other electrical discharge devices, such as rectifier apparatus and tubes and the like.

What is claimed is:

1. An X-ray tube housing comprising a chamber composed of dielectric material, a socket secured to said chamber, said socket being adapted to receive the anode terminal of an X-ray tube, a radiator secured to said socket and extending outwardly from said chamber, a plurality of dielectric walls united to a wall of said chamber in socket and extending from walls being located withan x-ray apparatus,

said wall said dielectric in said chamber.

2. An X-ray tube housing comprising a dielectric chamber having a base and a side wall, a socket secured to said base and forming an oil tight seal with said base, a radiator secured to said socket and'extending outwardly from said base, a plurality of dielectric walls secured to said base, each dielectric wall forming an annulus with the side wall of said chamber.

3. An X-ray apparatus including a dielectric chamber, an electric conductor in one wall thereof, dielectric baflle means in said chamber and extending from an inner wall surface thereof, and an X-ray tube having an envelope and a plurality of high'tension electrode terminals, one of said terminals being electrically connected to said conductors, the distance between said terminals measured outside of the tube when not mounted being less than the critical ambient gap of the tube, said tube being mounted in said chamber, said bailie means being adjacent a wall of said envelope and spaced therefrom, the length of the ambient gap of the tube mounted being as great as said critical gap.

4. An X-ray apparatus including an X-ray tube in air and having high tension electrode terminals and an envelope, the shortest distance between said terminals measured outside of said tube when not mounted being less than the critical ambient air gap of said tube, and a dielectric chamber having an electric socket in one of its walls, and dielectric bafile means in said chamber, said X-ray tube being mounted in said chamber and having one terminal thereof in said socket, said baille means being adjacent a wall of said envelope, the length of the ambient air gap of the so mounted tube being as great as the critical air gap of said tube.

5. An X-ray apparatus including an X-ray tube in air, said tube having an envelope, a cathode terminal and an anode terminal, the shortest distance between said terminals measured externally of said tube when not mounted being less than the critical ambient air gap of the tube, a dielectric chamber having an electrical socket in one of the walls th :reof, dielectric baflle means in said chamber and extending from one of the walls thereof, said envelope having a body portion and dielectric means integral therewith, said dielectric means having a portion thereof spaced from said body portion, said X- ray tube being mounted in said chamber with the anode terminal being located in said socket, said dielectric baflle means being located in the space between said dielectric means and said body portion of said X-ray tube, the length of the ambient air gap of the so mounted tube being as great as the critical ambient air gap of the tube.

6. An X-ray apparatus including an X-ray tube having an envelope and spaced high tension electrode terminals, a portion of said enevelope being in-the form of a plurality of sleeves, one of said sleeves being integrally united with and having a portion thereof spaced from another sleeve, a dielectric chamber having an electric socket in one wall thereof, and dielectric bailie means in said chamber and extending from the inner wall surface thereof, said tube being mounted in said chamber with said baflle means located in the space between said sleeves, one of said terminals being electrically connected to said socket.

'7. An X-ray apparatus including an X-ray tube having an envelope and spaced high tension terminals, the envelope having a portion thereof in the form of a plurality of spaced cylinders, and a dielectric chamber, said chamber having an electric socket in one wall thereof, a cylindrical dielectric baiile extending from the inner wall surface of said chamber, said tube being located in said chamber, one of said terminals being electrically connected to said socket, said bafile being located in the space between said cylinders.

8. An X-ray apparatus including an X-ray tube having an envelope and spaced high tension electrode terminals a portion of said envelope being in the form of spaced folds, a dielectric chamber, said chamber having a dielectric baflie means secured thereto and extending from the inner wall surface thereof, said tube being located in said chamber, said baflle being located in the space between said folds, said chamber having an electric conductor therein one of said terminals being electrically connected to said conductor.

9. An X-ray apparatus including an X-ray tube having an envelope and spaced high tension electrode terminals, said envelope having a portion thereof in the form of spaced concentric cylinders, a dielectric chamber having a conductor secured thereto, a cylindrical baflle means secured to said chamber and located therein, said tube being located in said chamber, one of said terminals being electrically connected to said conductor, said cylindrical bafile being located in the space between said spaced cylinders.

10. An X-ray apparatus including an X-ray tube in air and having an envelope and high tension electrode terminals, a casing containing oil and a transformer immersed therein and connected to said X-ray tube for energizing the same, a dielectric chamber carried by said casing and being immersed in said oil, an electric conductor secured to one of the walls of said chamber, said X-ray tube being mounted in said chamber, one of said terminals being electrically connected to said conductor, the distance between the electrode terminals of said tube measured outside of said tube and when not mounted being less than the critical ambient air gap of said tube, said dielectric chamber including dielectric baflie means for increasing the ambient air gap of the tube, the ambient air gap of the tube when mounted in said chamber being at least as great as the critical air gap of the tube.

11. An X-ray apparatus including an X-ray tube in air and having an envelope and a plurality of spaced high tension terminals, said envelope having a portion thereof in the form of a plurality of spaced cylinders, a casing, a dielectric liquid in said casing and a transformer immersed in said liquid and connected to said X-ray tube for energizing the same, a dielectric chamber carried by said casing and immersed in said liquid, a dielectric baflle secured to said chamber and extending from the inner wall surface thereof, a socket'carried by said chamber, one of said terminals being located in said socket, said tube being located in said chamber, said baflle being located in the space between said spaced cylinders.

WILLIAM A. McKAY. 

